fix(renovate): exclude symfony/monolog-bundle from the ~7.4 Symfony rule

monolog-bundle is versioned independently (4.x) and has no 7.4 releases,
so the allowedVersions constraint blocked all its updates.

Closes #39

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

renovate.json

@@ -15,6 +15,7 @@
       "matchPackageNames": [
         "/^symfony//",
         "!symfony/flex",
+        "!symfony/monolog-bundle",
         "!/^symfony/polyfill-/",
         "!/-contracts$/"
       ]